/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.catalina.tribes.util;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * ThreadFactory implementation that creates threads with the thread context
 * class loader set to the class loader that loaded this factory. It is intended
 * to be used when tasks may be passed to executors when the web application
 * class loader is set as the thread context class loader, such as in async
 * session replication.
 */
public class TcclThreadFactory implements ThreadFactory {

	private static final AtomicInteger poolNumber = new AtomicInteger(1);
	private static final boolean IS_SECURITY_ENABLED =
			(System.getSecurityManager() != null);

	private final ThreadGroup group;
	private final AtomicInteger threadNumber = new AtomicInteger(1);
	private final String namePrefix;

	public TcclThreadFactory() {
		this("pool-" + poolNumber.getAndIncrement() + "-thread-");
	}

	public TcclThreadFactory(String namePrefix) {
		SecurityManager s = System.getSecurityManager();
		group = (s != null) ? s.getThreadGroup() : Thread.currentThread().getThreadGroup();
		this.namePrefix = namePrefix;
	}

	@Override
	public Thread newThread(Runnable r) {
		final Thread t = new Thread(group, r, namePrefix +
				threadNumber.getAndIncrement());

		if (IS_SECURITY_ENABLED) {
			AccessController.doPrivileged(new PrivilegedAction<Void>() {
				@Override
				public Void run() {
					t.setContextClassLoader(this.getClass().getClassLoader());
					return null;
				}
			});
		} else {
			t.setContextClassLoader(this.getClass().getClassLoader());
		}
		t.setDaemon(true);
		return t;
	}

}
